HOUSTON -- Jay Bruce got off to a slower than expected start this season.

He soon warmed up, and with the postseason approaching, the Cincinnati slugger certainly isn't slowing down.

Bruce hit a grand slam and had five RBIs, Mike Leake pitched eight scoreless innings and the Reds cruised to a 10-0 win over Houston on Tuesday night, handing the Astros their 100th loss.

The home run was Bruce's 30th, giving him at least 30 homers in three straight seasons. His performance pushed his RBI total to 100, which is a career high.

"Thirty home runs is almost automatic if he stays healthy because that's his swing," manager Dusty Baker said. "But it was great to see him get his 100 RBIs, especially with the fact that he started off struggling in the RBI department.

"We had (Sin-Soo) Choo on all the time and we had Joey (Votto) on all the time and he had quite a few chances. Now he's cashing them in and hopefully it continues into the playoffs."

Cincinnati is 4 1/2 games ahead of Washington for second NL wild card.

The Astros are the first major league team to lose at least 100 games in three straight seasons since Kansas City from 2004-06.

"I'm always going to concentrate on the things we need to do to improve," Houston manager Bo Porter said when asked about losing 100 games. "I don't concern myself with what it is people are going to say. I concern myself about the men in that clubhouse and how we're going to get better every day."

The Reds got to work early, with Zack Cozart driving in two runs in a four-run first inning.

Cincinnati was up by five in the fourth before Bruce's towering slam to the Crawford Boxes in left field pushed the lead to 9-0 and chased Jordan Lyles (7-8).

Leake (14-6) allowed five hits over eight innings and struck out six with two walks.

Sean Marshall, who hadn't pitched since May 20 because of shoulder tendinitis, threw a perfect ninth to complete the shutout.

The Reds tagged Lyles for nine hits and nine runs in 3 1/3 innings.

The Astros, who have the worst record in the majors, fell to 51-100. They were 56-106 in 2011 and dropped to 55-107 last year, their final season in the National League.

With a rookie-filled team and the lowest payroll in the majors, the Astros have had plenty of lopsided games this year.

But even in an already dismal year, the night they eclipsed the century mark yet again was particularly ugly.

Things went downhill quickly for the Astros. Lyles had a two-base error when he fielded a high-bouncing grounder hit by Brandon Phillips and badly overthrew first base with one out in the first.

An RBI single by Bruce made it 1-0. Xavier Paul walked to load the bases and Todd Frazier's single pushed the lead to 2-0.

Cozart wrapped up the scoring in that inning with a two-RBI single to make it 4-0.

The bottom of the first didn't go any better for Houston. Jonathan Villar hit a leadoff single, but was thrown out trying to stretch it into a double. But it wasn't just that he was thrown out, but the way he was thrown out that was embarrassing.

Villar slid into second base, but Phillips already had the ball before he began the slide. The always flamboyant Phillips reached backward between his legs to apply the tag as Villar crashed head-first into Phillips' backside.

"That's the way I play," Villar said. "I'm aggressive. I was trying to make something happen, motivate my team. It's hard to change because that's the way I've always played."

Phillips said he wasn't trying to showboat, and he initially didn't realize that Villar was coming.

"The crowd let me know that he was coming to second base," Phillips said. "I just had to quickly put the tag between my legs. That's the only reason I tagged him. If I didn't hear the crowd, I would have just caught it and looked around and he would have been safe."

However, he probably could have tagged him in a less showy way.

"That's me," he said with a laugh. "I do things off the wall, yes."

Baker laughed when asked about the play.

"Ask Brandon," he said. "I think he gets bored sometimes."

Cozart added an RBI single in the third to extend Cincinnati's lead to 5-0.

Derrick Robinson walked with no outs in the fourth inning before Shin-Soo Choo drew a walk. A one-out walk by Votto loaded the bases to set up the slam by Bruce, which chased Lyles. It was his first grand slam since Sept. 5, 2008.

Game notes
The series wraps up on Wednesday when Houston's Brad Peacock opposes Greg Reynolds. ... Votto extended his hitting streak at Minute Maid Park to 23 games, which is the longest by a player in the park's history.